Moonroofs are popular options on vehicles of all types, as they allow additional light into a vehicle's interior, as well as provide a view above the car. Moonroofs are often configured with a powered drive mechanism that allows the moonroof to open to varying degrees, depending upon the moonroof's configuration, thereby allowing fresh air to enter and hot air to easily escape a vehicle's interior.
Known powered moonroofs are not entirely satisfactory for the range of applications in which they are employed. For example, existing powered moonroof mechanisms can be bulky, consisting of a somewhat bulky conventional DC motor that is mechanically connected to a geared drive. The geared drive in turn converts the motor's rotary motion into a linear motion, which is then imparted to the moonroof's glass panel by way of a cable mechanism that is attached to the glass panel. This type of drive is known as a “regulator”, and has long been used in vehicle power window mechanisms.
This type of mechanism tends to be bulky, requiring space for a relatively large drive motor and its associated geared drive and cable mechanism. Larger moonroofs require correspondingly larger motors, and more robust geared drives and cables to support the greater forces required to move larger panels. Vehicle designers must provide such space in the form of one or more cavities in a vehicle's roof to accommodate a moonroof utilizing a conventional drive mechanism. These cavities can increase the size and bulk of a vehicle roof, and present a potential obstacle that must be avoided when designing or incorporating safety features such as a roll bar that must also pass through a vehicle's roof. The conventional sunroof cassette also lowers headroom significantly. In addition, conventional moonroof drive mechanisms can be somewhat noisy, generating noise similar to that of a power window mechanism.
Thus, there exists a need for moonroofs with a power drive mechanism that improves upon and advances the design of known powered moonroofs, including consuming less package space, easily scaling to larger sized moonroofs, and providing a potentially quieter mechanism. One solution is to use a linear motor to directly drive the moonroof, where the glass panel can be directly attached to the rotor portion of the linear motor. Such an implementation avoids the necessity of a separate motor, gear drive and cable assembly, and can potentially operate more quietly, as no gearing is necessary to power the moonroof provided the components of the linear motor are configured properly. Examples of new and useful powered moonroofs relevant to the needs existing in the field are discussed below.
In the prior art, German patent publication DE 195 40 769 C1 to Hahn et al. (“Hahn”) discloses a moonroof that is driven by a linear motor assembly. Specifically, Hahn discloses a channel-shaped stator equipped with a series of coils that magnetically engage with a rail-shaped guide equipped with magnets, that is configured as a rotor. The moonroof's glass sheet is attached to the rail-shaped guide, which can then impart a force along the axis of travel for the glass sheet when the stator coils are energized.
An alternative arrangement where the rotor contains coils to be energized and the stator is comprised of magnets is found in U.S. Pat. No. 6,664,664 to Botos et al. (“Botos”). Botos describes a linear motor where the coils are placed in the rotor, which is disclosed as a printed circuit board where coils are comprised of a series of electrical traces, arranged in several layers. The layers are energized simultaneously to create a directional magnetic field which interacts with the stator magnets to cause the linear rotor to move.